|
Antimony Trisulfide
Antimony trisulfide (Sb2S3) is found in nature as the crystalline mineral stibnite and the amorphous red mineral (actually a mineraloid) metastibnite. It is manufactured for use in safety matches, military ammunition, explosives and fireworks. It also is used in the production of ruby-colored glass and in plastics as a flame retardant. Historically the stibnite form was used as a grey pigment in paintings produced in the 16th century. In 1817, the dye and fabric chemist, John Mercer discovered the non-stoichiometric compound Antimony Orange (approximate formula2 Sb2S3•Sb2O3), the first good orange pigment available for cotton fabric printing. Antimony trisulfide was also used as the image sensitive photoconductor in vidicon camera tubes. It is a semiconductor with a direct band gap of 1.8–2.5 eV. With suitable doping, p and n type materials can be produced. Preparation and reactions Sb2S3 can be prepared from the elements at temperature 500–900 °C: :2 Sb + 3 S â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimony Trioxide
Antimony(III) oxide is the inorganic compound with the formula Sb2O3. It is the most important commercial compound of antimony. It is found in nature as the minerals valentinite and senarmontite. Like most polymeric oxides, Sb2O3 dissolves in aqueous solutions with hydrolysis. A mixed arsenic-antimony oxide occurs in nature as the very rare mineral stibioclaudetite. Production and properties Global production of antimony(III) oxide in 2012 was 130,000 tonnes, an increase from 112,600 tonnes in 2002. China produces the largest share followed by US/Mexico, Europe, Japan and South Africa and other countries (2%). As of 2010, antimony(III) oxide was produced at four sites in EU27. It is produced via two routes, re-volatilizing of crude antimony(III) oxide and by oxidation of antimony metal. Oxidation of antimony metal dominates in Europe. Several processes for the production of crude antimony(III) oxide or metallic antimony from virgin material. The choice of process depends on th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Textile Printing
Textile printing is the process of applying color to fabric in definite patterns or designs. In properly printed fabrics the colour is bonded with the fibre, so as to resist washing and friction. Textile printing is related to dyeing but in dyeing properly the whole fabric is uniformly covered with one colour, whereas in printing one or more colours are applied to it in certain parts only, and in sharply defined patterns. In printing, wooden blocks, stencils, engraved plates, rollers, or silkscreens can be used to place colours on the fabric. Colourants used in printing contain dyes thickened to prevent the colour from spreading by capillary attraction beyond the limits of a pattern or design. History Woodblock printing is a technique for printing text, images or patterns used widely throughout East Asia and probably originating in China in antiquity as a method of printing on textiles and later paper. As a method of printing on cloth, the earliest surviving examples from C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schlippe's Salt
Sodium thioantimoniate or sodium tetrathioantimonate(V) is an inorganic compound with the formula . The nonahydrate of this chemical, , is known as Schlippe's salt, named after Johann Karl Friedrich von Schlippe (1799–1867), These compounds are examples of sulfosalts. They were once of interest as species generated in qualitative inorganic analysis. Structure left, Anhydrous NaSbS3 has a complicated structure featuring SbS4- tetrahedra interconnected by Na-S bonds. Color scheme: red = Sb, yellow = S, violet = Na. The nonahydrate consists of the tetrahedral tetrathioantimonate(V) anions and sodium cations , which are hydrated. The Sb-S distance is 2.33 Å. Related salts are known for different cations including ammonium and potassium. The anhydrous salt is a polymer with tetrahedral Na and Sb sites. Preparation Sodium tetrathioantimonate nonahydrate is prepared by the reaction of "antimony trisulfide", elemental sulfur, and aqueous sulfide source. : The Na2S can be generated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaret-Ann Armour
Margaret-Ann Armour (6 September 1939 – 25 May 2019) was a Scottish-born Canadian chemist based at the University of Alberta. She is best known for her expertise in developing guidelines for hazardous lab waste disposal, and for being a vocal advocate for women in science. Armour founded the Women in Scholarship, Engineering, Science and Technology (WISEST) program, and served as the first and only Associate Dean of Science for Diversity at the University of Alberta. Among her many honors, she was named a member of the Order of Canada (2006), a 3M Teaching Fellow (1996) and a Canada 150 ambassador (2017). Early life and education Armour was born in Glasgow, Scotland on 6 September 1939, Her father died during World War II, and she was raised by her mother (a teacher). Armour and her mother lived in a town between Dundee and Aberdeen, before moving to Penicuik, where Armour attended the local Lasswade school. Her natural curiosity for science was fostered there by her chemist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrochloric Acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H+, and an anion, A-. The dissociation of a strong acid in solution is effectively complete, except in its most concentrated solutions .... It is a component of the gastric acid in the digestive systems of most animal species, including humans. Hydrochloric acid is an important laboratory reagent and industrial chemical. History In the early tenth century, the Persian physician and alchemist Abu Bakr al-Razi ( 865–925, Latin: Rhazes) conducted experiments with sal ammoniac (ammonium chloride) and vitriol (hydrated sulfates of various metals), which he distilled together, thus producing the gas hydrogen chloride. In doing so, al-Razi may have stumbled upon a primitive method ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures is ''stinkdamp''. Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. The British English spelling of this compound is hydrogen sulphide, a spelling no longer recommended by the Royal Society of Chemistry or the International Union of Pure and Applied Chemistry. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide. When it is inhaled or it or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrinsic Semiconductor
An extrinsic semiconductor is one that has been '' doped''; during manufacture of the semiconductor crystal a trace element or chemical called a doping agent has been incorporated chemically into the crystal, for the purpose of giving it different electrical properties than the pure semiconductor crystal, which is called an ''intrinsic semiconductor''. In an extrinsic semiconductor it is these foreign dopant atoms in the crystal lattice that mainly provide the charge carriers which carry electric current through the crystal. The doping agents used are of two types, resulting in two types of extrinsic semiconductor. An ''electron donor'' dopant is an atom which, when incorporated in the crystal, releases a mobile conduction electron into the crystal lattice. An extrinsic semiconductor which has been doped with electron donor atoms is called an n-type semiconductor, because the majority of charge carriers in the crystal are negative electrons. An '' electron acceptor'' dopant is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor
A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glass. Its electrical resistivity and conductivity, resistivity falls as its temperature rises; metals behave in the opposite way. Its conducting properties may be altered in useful ways by introducing impurities ("doping (semiconductor), doping") into the crystal structure. When two differently doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second-most common s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vidicon
Video camera tubes were devices based on the cathode ray tube that were used in television cameras to capture television images, prior to the introduction of charge-coupled device (CCD) image sensors in the 1980s. Several different types of tubes were in use from the early 1930s, and as late as the 1990s. In these tubes, an cathode ray, electron beam was scanned across an image of the scene to be broadcast focused on a target. This generated a current that was dependent on the brightness of the image on the target at the scan point. The size of the striking ray was tiny compared to the size of the target, allowing 483 horizontal scan lines per image in the NTSC format, 576 lines in PAL, and as many as 1035 lines in Multiple sub-Nyquist sampling encoding, Hi-Vision. Cathode ray tube Any vacuum tube which operates using a focused beam of electrons, originally called cathode rays, is known as a cathode ray tube (CRT). These are usually seen as display devices as used in older (i.e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoconductor
Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation. When light is absorbed by a material such as a semiconductor, the number of free electrons and holes increases, resulting in increased electrical conductivity. To cause excitation, the light that strikes the semiconductor must have enough energy to raise electrons across the band gap, or to excite the impurities within the band gap. When a bias voltage and a load resistor are used in series with the semiconductor, a voltage drop across the load resistors can be measured when the change in electrical conductivity of the material varies the current through the circuit. Classic examples of photoconductive materials include: * photographic film: Kodachrome, Fujifilm, Agfachrome, Ilford, ''etc.'', based on silver sulfide and silver bromide. * the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-stoichiometric Compound
In chemistry, non-stoichiometric compounds are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers (i.e. an empirical formula); most often, in such materials, some small percentage of atoms are missing or too many atoms are packed into an otherwise perfect lattice work. Contrary to earlier definitions, modern understanding of non-stoichiometric compounds view them as homogeneous, and not mixtures of stoichiometric chemical compounds. Since the solids are overall electrically neutral, the defect is compensated by a change in the charge of other atoms in the solid, either by changing their oxidation state, or by replacing them with atoms of different elements with a different charge. Many metal oxides and sulfides have non-stoichiometric examples; for example, stoichiometric iron(II) oxide, which is rare, has the formula , whereas the more common material is nonstoichi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimony Triselenide
Antimony triselenide is the chemical compound with the formula Sb2 Se3. The material exists as the sulfosalt mineral antimonselite ( IMA symbol: Atm), which crystallizes in an orthorhombic space group. In this compound, antimony has a formal oxidation state +3 and selenium −2. The bonding in this compound has covalent character as evidenced by the black color and semiconducting properties of this and related materials. The low-frequency dielectric constant (ε0) has been measured to be 133 along the ''c'' axis of the crystal at room temperature, which is unusually large. Its band gap is 1.18 eV at room temperature. The compound may be formed by the reaction of antimony with selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ... and has a melting point of 885 K. Applic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
